1. Field of the Invention
This invention relates to solder extractors and to heater assemblies for use therewith and, in particular, to in-line solder extractors and their associated heater assemblies.
2. Discussion of the Prior Art
In general a solder extractor is utilized to melt and remove molten solder from a printed circuit board on the like in connection with the repair or production of an electronic assembly. The molten solder is drawn through a tubular tip, upon application of a vacuum thereto, into a solder collection chamber. In prior art extractors, such as those disclosed in U.S. Pat. Nos. 4,328,920 and 4,439,667, there are the following advantageous features: (a) optimized tip to grip ratio, (b) a quick connect, removable solder collecting chamber and sealing system, and (c) a high heat, low energy consumption heater assembly and desoldering tip combination. These desolderers are useful in many applications. In some applications however, there may be a shortcoming in that the forward seal for the solder collection chamber is mounted in direct contact with a mounting flange disposed on the outer sleeve of the heater assembly. Since the outer sleeve and flange tend to conduct heat from the heat source of the assembly, the direct mounting of the forward seal with respect to these parts can be undesirable in terms of seal longevity. That is, the seal tends to be subjected to high temperatures, which in turn reduces the life thereof thereby possibly impairing the seal or at least necessitating relatively frequent replacement thereof.
Other arrangements for mounting the seal for the forward end of the solder collection chamber are disclosed in U.S. Pat. No. 4,269,343. Thus, in FIG. 1 thereof, the seal is mounted directly on the riser or solder transfer tube extending from the bobbin or heater element support tube. In FIGS. 2 through 5, certain arrangements are disclosed for mounting the seal with respect to but removed from the riser tube while in FIGS. 6 through 10 thereof, the forward seal is mounted with respect to but spaced from the bobbin. Finally, in FIGS. 11 through 15 thereof, the forward seal is mounted with respect to the outer sleeve of the heater assembly. Some of these arrangements and, in particular the arrangement of FIGS. 6 through 10, have proved particularly advantageous in larger solder extractors. However, in certain applications, especially the growing number of applications involving close work on a densely packed printed circuit boards, reduction in the size of the solder extractor becomes an important consideration to facilitate manipulation thereof. Such smaller extractors are disclosed in the above mentioned U.S. Pat. Nos. 4,328,920 and 4,439,667; however, as stated above these extractors are sometimes subject to a shortcoming in terms of seal longevity.
All of the above mentioned prior art extractors are in-line extractors - that is, extractors where the heater assembly is tubular and the extracted solder flows from the tip through the heater assembly into a solder collection chamber which is mounted at least partially within the handle. Such in-line extractors have particular problems with the forward seal since it is disposed close to the heater assembly while at the same time being disposed within the handle where there is a limited circulation of air available. Hence, the problem of seal longevity is particularly aggravated in such extractors.
Another type of extractor known as a piggy-back extractor is disclosed in U.S. Pat. No. 3,970,234. In this type of extractor, the heater assembly is not tubular; rather, a soldering iron or the like is used as a heat source and a tubular solder transfer member is attached to the forward end of the iron whereby molten solder can be drawn through the tube into a solder collection chamber disposed outside and substantially removed from the handle upon application of a vacuum. In the extractor disclosed in U.S. Pat. No. 3,970,234, the seal is mounted with respect to a cylindrical seal mounting member which, in turn, is mounted on the solder transfer tube. This type of seal mounting is necessary in the above piggy-back device in that the solder collection tube is supported only at its forward end and thus the foregoing mounting means must be employed to effect secure mounting for the solder collection tube. Such is not the case in an in-line extractor where the solder collection tube is supported and sealed both at its forward and rearward ends. Accordingly, the designer is provided with much greater flexibility in determining the optimum manner for mounting the forward seal with respect to the heater assembly in an in-line extractor.
All of the patents mentioned above are incorporated herein by reference.